1. Field of the Invention
The invention relates to a remote control system and a mobile device and, more particularly, to a remote control system and mobile device that control an in-vehicle device.
2. Description of the Related Art
There has been developed a remote control system in the existing art. In the remote control system, a user operates a mobile device to transmit a wireless signal from the mobile device and then an in-vehicle device, such as a door lock device, is controlled in response to the wireless signal.
Japanese Patent Application Publication No. 2008-60942 (JP-A-2008-60942) describes an example of a mobile device used in the above remote control system. The mobile device described in JP-A-2008-60942 wirelessly transmits a command signal for controlling a control target in response to user's input. The mobile device is able to transmit wireless signals of a plurality of different frequencies, and transmits the command signal at one frequency set as a transmission frequency among the plurality of frequencies. Then, the user carries out a predetermined operation to change the transmission frequency to any one of the plurality of frequencies.
With the mobile device described in JP-A-2008-60942, when a wireless signal having a set transmission frequency is not normally received by a receiver because of the influence of noise, or the like, of electromagnetic waves and then communication is not established between the mobile device and the receiver, the user carries out an operation for switching the set transmission frequency to thereby make it possible to change the transmission frequency to a frequency that is insusceptible to the influence of noise, or the like. That is, the user carries out an operation for switching the transmission frequency to thereby make it possible to improve the capability of establishing communication between the mobile device and the receiver.
However, in the mobile device described in JP-A-2008-60942, the set transmission frequency cannot be changed until the user carries out an operation for switching the transmission frequency. Thus, under a situation that communication between the mobile device and the receiver is not established, unless the user carries out an operation for switching the transmission frequency, it may be impossible to establish communication between the mobile device and the receiver.